1. Field of the Invention
This invention relates generally to hypodermic needles for injecting medicines intramuscularly, intravenously or into intravenous administration systems, and more particularly relates to apparatus for retaining hazardous fluid, such as chemotherapy agents, ejected in priming such a needle by purging air from the needle.
2. Description of Related Art
Current practice in preparing hypodermic syringes for injecting fluid medicines into the body of a patient typically involves priming the hypodermic needle by purging air from the needle and ejecting a small portion of the fluid from the needle of the syringe to insure that air has been removed from the syringe and the needle, to avoid causing an air embolism in the patient. The fluid is typically squirted into the air or onto an absorbant material, but in cases where the fluid is hazardous to the medical personnel preparing the injection, the fluid is commonly ejected into an appropriate waste container, which may result in accidental spattering of the fluid out of the waste container where it can be dangerous.
Another approach to purging air from a hypodermic needle by ejecting the air and a portion of a hazardous fluid from a hypodermic needle involves ejecting the air and fluid into a specially sealed needle guard sheath designed to retain the fluid. One such needle guard sheath includes a pad of absorbant material for absorbing the hazardous fluid, and an agent such as bleach in the absorbant pad for neutralizing the hazardous fluid. A buildup of pressure in such a sealed sheath can prevent effective purging of the syringe needle if the amount of air and fluid that must be purged to prime the syringe needle exceeds the capacity of the sheath. An absorbant pad or filter can to some extent prevent the escape of hazardous fluid from a vented purging sheath, but it has been found that the spray of fluid from the needle can also penetrate such a pad if the force of the spray is sufficient. One such needle guard sheath includes a vent with a hydrophobic filter to retain fluid while allowing the flow of air through the filter. It has been found that the flow of air through such a hydrophobic filter can also be blocked by an accumulation of the spray of fluid on the filter, allowing pressure buildup within the sheath to interfere with effective purging of air in priming the syringe needle. It would therefore be desirable to provide a sheath for a hypodermic needle which would vent air purged from the needle, but which would retain any hazardous fluid also ejected from the needle, and which would avoid blockage of an air vent by the fluid.
Conventional needle guard sheaths frequently also allow technicians to accidentally stick themselves with the hypodermic needle in placing the sheath over the needle. A flange at the base of the sheath can help to protect the hands of the technician from the needle to some extent, but it would be desirable to provide a needle guard sheath removably mounted on a hypodermic needle, adapted to be connected to a syringe or I.V. administration set used for supplying hazardous fluid to be administered through the needle, so that the needle can be connected to the syringe or I.V. administration set, purged of air and primed, without risk of needle sticks to the technician.